Recently, devices designed to handle images as digital data, e.g., digital cameras and digital video recorders, have become popular.
A pan head camera is also used, which is designed to control moving images from a remote place or automatically control them, as represented by WebView.
Along with these tendencies, some of the conventionally used cameras which record dates, hours, shutter speeds, and exposure information, and can be controlled are designed to attach, to images, not only information such as a pan angle, tilt angle, and field angle as attributes, but also various control information and supplementary information (e.g., temperature and weather) for images as attributes.
In addition, surveillance systems using such cameras are used, and photographed images are stored and used.
In general, however, an enormous number of images are photographed by a surveillance system, and a search is made on the basis of the date/hour of photography. However, a found image is not always the one requested by a user.
As disclosed in Japanese Patent Laid-Open Nos. 2000-235637 and 2000-235638, in some cases, image searches are made on the basis of similarities themselves among image data.
By using similarities between images, for example, images similar to a query image can be found or a scene change in a TV program can be detected by obtaining a change point.
However, images obtained by searches using similarities between image data do not always coincide with images wanted by users.
This is because, it is difficult to obtain a similarity in consideration of all conditions at the time of photography by using only an algorithm for obtaining a similarity itself between images.
In addition, when image data are accumulated for surveillance, the number of search targets becomes huge, and it is important to narrow down to necessary target images.
Furthermore, in photography by a moving camera, different images are sensed depending on control. Even if, therefore, different objects are photographed, similar images may be photographed when the objects are similar in color or shape.